How to update RDS instance (SingleAZ – Multi AZ)

I got the following message from amazon.

Dear Amazon RDS Customer,

A system update is now available for any Amazon RDS PostgreSQL database instances you created before 13 October 2015. We recommend installing this update to take advantage of several performance improvements and security fixes. You may choose to install this update immediately, or during your next scheduled maintenance window. After approximately six weeks, your RDS instance will be automatically upgraded during your maintenance window. To learn more about scheduling or installing an upgrade, please refer to the RDS documentation:

Installing this update will have an availability impact for a few minutes on your RDS instance (60-120 seconds for Multi-AZ instances). To reduce downtime, you may consider converting your Single-AZ instances to Multi-AZ. If you have any questions or concerns, please contact your TAM or AWS Support.

The Amazon RDS Team

So, we decided to update RDS manually by ourselves.
We had three instances running simultaneously: development, staging and production. Each server is running on SingleAZ, so in order to reduce downtime, we shifted from Single-AZ to Muti-AZ, then updated RDS and put it back to Single-AZ again. In this article, we’ll cover the process.  This is pretty much straight-forward but when you shifted back from Multi-AZ to Shift-AZ, make sure you’ll have the same AZ as your EC2 instance. Having different AZ on RDS from EC2 will affect connection speed.

  1. Go to RDS.
    Screen Shot 2016-01-20 at 1.02.40 PM
  2. Select an DB instance and check Availability Zone.
    Screen Shot 2016-01-20 at 1.02.53 PM
  3. Go to “Instance Action” and select “Modify”. Check “Multi AZ” and “Apply Immediately”.
    Screen Shot 2016-01-20 at 1.23.40 PM
  4. Go to “Instance Action” and select “Upgrade Now”.
  5. After the maintenance, you can see the RDS instance failovered automatically.
    Screen Shot 2016-01-20 at 1.35.14 PM
  6. Now, you have to put it back to Single AZ. However, if you just modify just like we did above, the new AZ will be used and you don’t wanna use different AZ from EC2.  In order to avoid that, you need to reboot the instance by checking “Reboot with failover”, which will bring the secondary AZ (desired AZ) to the primary AZ.

    Screen Shot 2016-01-20 at 1.41.47 PM

  7. Lastly, do not forget to shift back to Single AZ,  click “Modify”,  uncheck “Multi AZ” and check “Apply Immediately”.

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